In a screen printing device, first, a paste or ink coating material supplied on a screen plate is coated by a scraper evenly over the screen plate. A squeegee is then brought into contact with the screen plate and moved thereon, thereby printing a predetermined pattern on a printed material under the screen plate (see, for example, Patent Literature 1 and Patent Literature 2).
However, when such a scraper is used to repeat screen printing, the paste or ink coating material on the screen plate flows over and around both ends in the width-direction of the scraper to outside thereof. According to Patent Literature 1, it is supposed that the cause of this is that when both end portions of a scraper are solely bent inward relative to a traveling direction of the scraper, a coating material at the both end portions of the scraper only rolls up and down along a screen plate repeatedly, and therefore is not brought near a printing pattern portion on the screen plate.
The coating material flowing over and around the both ends of the scraper to the outside is left for a long time during an operation of the screen printing device. Therefore, due to causes such as significant changes in the viscosity by vaporization of volatile components of the coating material, the coating material cannot be reused. Accordingly, the flow of the coating material over and around the both ends of the scraper becomes a cause of the material loss.
Therefore, in order to solve this problem, there is proposed a screen printing device scraper that can reduce the material loss by reducing a flow amount of a coating material (see, for example, Patent Literature 1, Patent Literature 2, Patent Literature 3, and Patent Literature 4). For example, in Patent Literature 1, a member including an upwardly-inclined portion is attached to both ends of a scraper, thereby reducing a flow of a coating material from the both ends of the scraper. In Patent Literature 2, a sub-scraper is provided, thereby reducing a flow of a coating material over and around both ends of a scraper. In Patent Literature 3, individually-formed members are coupled with a predetermined gap therebetween, thereby reducing a flow of a coating material over and around both ends of a scraper. In Patent Literature 4, a pre-squeegee is provided to serve as a sub-scraper, thereby reducing a flow of a coating material over and around both ends of a scraper.